Outlet passage construction for teeming vessels

ABSTRACT

A bottom pour-teeming vessel in which the walls of the outlet passage are equipped with an electric-heating coil. The passage walls may be formed of a zirconia or 90 percent alumina liner and a sleeve surrounding the liner but spaced radially therefrom. The heating coil winds about the liner in the space between it and the sleeve and the remainder of the space is filled with alumina powder. A layer of thermal insulation encloses the sleeve. The sleeve is supported on a refractory nut threaded on the lower end of the liner.

United States Patet Keith K. Kappmeyer Franklin Township, WestrnorelandCounty; James T. Shapland, Wilkins, Township,

[72] Inventors Allegheny County, both of Pa. [21] AppLNo. 840,215 [22]Filed July 9, 1969 [45] Patented Sept. 14, 1971 [73] Assignee UnitedStates Steel Corporation Continuation-impart of application Ser. No.698,514, Jan. 17, 1968, now abandoned.

[54] OUTLET PASSAGE CONSTRUCTION FOR TEEMING VESSELS 5 Claims, 7 DrawingFigs.

[52] 0.8. CI 222/146, 164/281 [51] Int. Cl 865d 5/62 [50] Field ofSearch 222/146 HE, l46;239/l33; 164/337, 119, 133;219/28l, 10.49, 10.51;266/38; 13/33 [56] References Cited UNITED STATES PATENTS 1,763,2296/1930 Fourment 2l9/10.5l X 2,324,337 7/1943 Jomsland 222/146 X3,028,874 4/1962 Burkett 266/38 X 3,367,646 2/1968 Robertson et al...266/38 X 3,435,992 4/1969 Tisdale et al 164/281 X 3,427,421 2/1969Matheson et al. 219/1099 3,501,068 3/1970 Shapland 222/561 X PrimaryExaminer- Sam uel F. Coleman A ssigqnt Examiner- Norman L. Stack, J r.Attorney-Walter P. Wood ABSTRACT: A bottom pour-teeming vessel in whichthe walls of the outlet passage are equipped with an electric-heatingcoil. The passage walls may be formed of a zirconia or 90 percentalumina liner and a sleeve surrounding the liner but spaced radiallytherefrom. The heating coil winds about the liner in the space betweenit and the sleeve and the remainder of the space is filled with aluminapowder. A layer of thermal insulation encloses the sleeve. The sleeve issupported on a refractory nut threaded on the lower end of the liner.

PATENTED SEP 1 4 I97: 3,604 598 sum 1 [1F 3 TIE-.1...

HI HH H' INVENTORS. 9 KEITH KKAPPMEYERE JAMES T. .SHAPLAND A t I mayPATENTEU SEP1 4mm 3.604.598

snw 2 OF 3 INVENTORS. 23 24 KEITH K. KAPPMEYER a JAMES T. SHAPLAND o- -FJ I J- 7 OUTLET PASSAGE CONSTRUCTION FOR TEEMING VESSELS Thisapplication is a continuation-in-part of our earlier application ser.No. 698,514, filed Jan. 17, 1968, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to an outlet passageconstruction for discharging a stream of molten metal from a teemingvessel such as a tundish.

In the continuous casting of steel, it is desirable to teem metal intothe conventional tubular flow-through mold at a temperature close to thesolidification point so that, on initial contact with the mold wall, themetal cools sufficiently to solidify and form a skin on the casting. Ithas been the practice to have outlet passages of small bore in thetundish from which metal is teemed into the mold in order to facilitateclose control of the volume of flow. As a result of both these factors,there is a tendency for the metal to freeze in the bore and restrictfurther flow therethrough. Wear of the conventional fire-clay nozzle inuse results in an uncontrolled increase in the size thereof as well asintroducing nonmetallic inclusions into the casting. An object of ourinvention is to provide a teeming-vessel nozzle or partially submergedpouring tube which is wear-resistant and has built-in heating means tolimit the freezing tendency of the metal teemed therethrough.

SUMMARY OF THE INVENTION In a present preferred embodiment of ourinvention, we provide a nozzle having a wear-resistant liner, athermally insulating exterior sleeve surrounding the liner with acylindrical space therebetween and an electric-resistance heating coilpositioned in said space and embedded in refractory material which isboth thermally and electrically insulating. The liner is preferably ofhigh-alumina refractory, i.e., 90 percent A or zirconia. The sleeve isof alumina or graphite and is surrounded by a layer of thermalinsulation. The coil is of graphite and the material embedding the coilis alumina powder. In a modification we provide a similar arrangement ina partially submerged pouring tube.

BRIEF DESCRIPTION OF THE INVENTION A complete understanding of theinvention may be obtained from the following detailed description andexplanation which refer to the accompanying drawings illustrating thepresent preferred embodiment. In the drawings:

FIG. 1 is an axial section through one form of our invention;

FIG. 2 is a similar view of a modification;

FIGS. 3 and 4 similarly show further modifications;

FIG. 5 is a developed view of the heating coil of the form of theinvention shown in FIG. 1;

FIG. 6 is an axial section showing another modification in which ourinvention is applied to a partially submerged pouring tube; and

FIG. 7 is a horizontal section on line VIIVII of FIG. 1.

DETAlLED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now indetail to the drawings and, for the present, particularly to FIG. 1, ateeming vessel 10, such as a tundish,

has a bottom outlet passage construction indicated generally at 11. Theoutlet passage is built into the lining 12 of the vessel which isenclosed within a shell 13 of steel plate. More specifically, the wallsof the outlet passage include a tubular metal neck 14 having a layer 15of castable thermally insulating material of any known kind, usuallyfire clay, which extends I It up into the vessel lining 11. neck 14 issupported Neck shell 13 by bolts 16.

The interior of the passage is formed of a nozzle liner 17 of end shapedto form a seat 18a for the lower end of the conven tional stopper rod(not shown). As shown, block 18 is embedded in the vessel lining l2 anda nut 19, also of the same material, is threaded on the lower end ofliner 17. A continw ous bore 20 extends through block 18 and liner 17 toconduct molten metal from vessel 10 to a mold therebelow.

A sleeve 21 of the same material as liner 17 extends between nut 19 andblock 18, surrounding liner 17 with a space therebetween. In this spaceis disposed a heating coil 22 having terminals brought out at 23 and 24through alumina tubes 25. The terminals extend radially through sleeve21, insulation layer 15 and neck 14 from separate semicircular segments26 of graphite (FIG. 7). Coil 22 is a doubled helix of graphite, thedeveloped form of which is a loop L shown in FIG. 5. The coil andsegments 26 may readily be formed by machining a cylinder molded fromgraphite. The space between liner l7 and sleeve 21 is filled withpowdered alumina 27 after insertion of coil 22 and segments 26,Provision may be made as shown at 28 for water-cooling terminals 23 and24.

Coil 22 is energized, before metal is to be teemed, as anelectrical-resistance heater, by alternating or direct current of highamperage. When so energized, the heat conducted to any skull or metalfrozen on the surface of bore 20 will tend to melt or, in any event,prevent building up of the skull to an objectionable extent. Thematerial of which liner 17, block 18 and sleeve 21 are composed, i.e.,zirconia or 90 percent alumina, is well suited to withstand both thetemperature of molten metal passing therethrough and the erosive actionof the stream.

FIG. 2 shows a modification. In this form of our invention, coil 22 hasupper and lower sections connected in parallel to segments 26. Inaddition, inner sleeve 29 of the same material as sleeve 21 isinterposed between coil 22 and liner 17. This construction permits liner17 to be replaced without removing coil 22 from its mounting betweensleeves 21 and 29.

FIG. 3 shows a further modification in which the segments 26 of FIG. 1are near the top of the spout. Semicylindrical segments 30 of graphitetake the place of sleeve 21 and also serve as conductors betweenterminals 23 and 24 an segments 26. Radial conductors 31 of graphiteconnect segments 30 and 26.

FIG. 4 shows a further modification in which segments 26 are above thecoil 22. In lieu of terminal 24, furthermore, one end of the coil isgrounded on shell 13 as at 32.

It will be evident that the modification of FIGS. 2-4 have all theadvantages of the construction of FIG. 1.

FIG. 6 shows portions of a conventional nozzle and receiving vessel 42,which is shown as a mold, either an openended mold used in continuouscasting or an ingot mold, but it may be some other type of vessel. Thenozzle forms part of a pouring vessel from which is suspended a pouringtube 43 constructed in accordance with our invention. The pouring vesselsupplies molten metal M, which is conducted through the nozzle and tubeinto the receiving vessel. As known in the art, the discharge end of thetube is submerged in liquid in the receiving vessel, whereby air isexcluded from the metal as it flows between the nozzle and receivingvessel.

In accordance with our invention, tube 43 comprises a refractory liner44, a sleeve formed of upper and lower refractory sections 45 and 46around the liner and a metal neck 47 around the upper sleeve section.The upper sleeve section 45 has upper and lower counterbores 48 and 49.The lower counterbore 49 has internal screw threads which engageexternal threads on the lower sleeve section 46. We mortar the threadedjoint between the two sections. The upper end of neck 47 has an externalflange 50 which we fasten to the tube suspending means. The lower end ofsleeve section 46 has an internal flange 51 which we mortar to the liner44 to prevent liquid metal from entering the lower end of the sleeve.

We place an electric-resistance heating coil 22 in the space between theliner 44 and the lower sleeve section 46. The coil is of similarconstruction to that used in the embodiments of FIGS. 1 to 4. It hasterminals 23 and 24 which extend radially through the upper sleevesection 45 from semicircular segments 26 of graphite. The segments arelonger than those used in the other embodiments, since the pouring tubeis longer than the nozzle, but otherwise similar. Coil 22 is locatedwhere it extends below the surface of liquid in the receiving vessel 42;hence it prevents freezing of metal both inside and outside the pouringtube.

We are aware that it is known to employ induction heating coils aroundoutlets from teeming vessels or the like, but this arrangement requiresthat the interior of the outlet contains solid metal. Ourelectric-resistance heating coil is effective for outlets, the interiorwalls of which are exclusively of refractory material.

We claim:

I. An outlet passage construction for a bottom pour teeming vesselcomprising an exclusively refractory liner extending downwardly form thevessel bottom, an electric-resistance heating coil around said liner,said coil being formed of a double helix of graphite, the developed formof which is a loop, semicircular graphite segments integral with therespective helices of said coil, terminals extending radially from saidsegments, and a refractory sleeve surrounding said coil.

2. A construction as defined in claim 1 comprising in addition a fillingof powdered refractory material within said sleeve embedding said coil.

3. A nozzle constructed as defined in claim 1 and comprising in additiona block integral with said liner adapted to be embedded in therefractory lining of the vessel.

4. An extended pouring tube constructed as defined in claim 1, saidsleeve being formed of upper and lower threadedly connected sections.

5. A construction as defined in claim 1 in which said coil is machinedfrom a molded graphite cylinder.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.- 559Dated September- 1 4, 1971 lnventofls) Keith K. Kappmeyer et 8.1

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 71, after "11.", "neck" should read Neck after"supported", "Neck" should read from Column 2, line 13, "doubled" shouldread double Column 2, line ho, "an" should read and Signed and sealedthis 10th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents USCOMM-DC DOING-POD v u s eovimmim wnlrnmu OFFICE Inso-zss-Ju.

RM PO-IOSO (10-69)

1. An outlet passage construction for a bottom pour teeming vesselcomprising an exclusively refractory liner extending downwardly form thevessel bottom, an electric-resistance heating coil around said liner,said coil being formed of a double helix of graphite, the developed formof which is a loop, semicircular graphite segments integral with therespective helices of said coil, terminals extending radially from saidsegments, and a refractory sleeve surrounding said coil.
 2. Aconstruction as defined in claim 1 comprising in addition a filling ofpowdered refractory material within said sleeve embedding said coil. 3.A nozzle constructed as defined in claim 1 and comprising in addition ablock integral with said liner adapted to be embedded in the refractorylining of the vessel.
 4. An extended pouring tube constructed as definedin claim 1, said sleeve being formed of upper and lower threadedlyconnected sections.
 5. A construction as defined in claim 1 in whichsaid coil is machined from a molded graphite cylinder.